Showing papers on "Hypovolemia published in 2004"

Clinical review: hemorrhagic shock.

Abstract: This review addresses the pathophysiology and treatment of hemorrhagic shock – a condition produced by rapid and significant loss of intravascular volume, which may lead sequentially to hemodynamic instability, decreases in oxygen delivery, decreased tissue perfusion, cellular hypoxia, organ damage, and death. Hemorrhagic shock can be rapidly fatal. The primary goals are to stop the bleeding and to restore circulating blood volume. Resuscitation may well depend on the estimated severity of hemorrhage. It now appears that patients with moderate hypotension from bleeding may benefit by delaying massive fluid resuscitation until they reach a definitive care facility. On the other hand, the use of intravenous fluids, crystalloids or colloids, and blood products can be life saving in those patients who are in severe hemorrhagic shock. The optimal method of resuscitation has not been clearly established. A hemoglobin level of 7–8 g/dl appears to be an appropriate threshold for transfusion in critically ill patients with no evidence of tissue hypoxia. However, maintaining a higher hemoglobin level of 10 g/dl is a reasonable goal in actively bleeding patients, the elderly, or individuals who are at risk for myocardial infarction. Moreover, hemoglobin concentration should not be the only therapeutic guide in actively bleeding patients. Instead, therapy should be aimed at restoring intravascular volume and adequate hemodynamic parameters.

Bench-to-bedside review: Sepsis is a disease of the microcirculation

Abstract: Microcirculatory perfusion is disturbed in sepsis. Recent research has shown that maintaining systemic blood pressure is associated with inadequate perfusion of the microcirculation in sepsis. Microcirculatory perfusion is regulated by an intricate interplay of many neuroendocrine and paracrine pathways, which makes blood flow though this microvascular network a heterogeneous process. Owing to an increased microcirculatory resistance, a maldistribution of blood flow occurs with a decreased systemic vascular resistance due to shunting phenomena. Therapy in shock is aimed at the optimization of cardiac function, arterial hemoglobin saturation and tissue perfusion. This will mean the correction of hypovolemia and the restoration of an evenly distributed microcirculatory flow and adequate oxygen transport. A practical clinical score for the definition of shock is proposed and a novel technique for bedside visualization of the capillary network is discussed, including its possible implications for the treatment of septic shock patients with vasodilators to open the microcirculation.

Epidural anesthesia, hypotension, and changes in intravascular volume.

Abstract: BackgroundThe most common side effect of epidural or spinal anesthesia is hypotension with functional hypovolemia prompting fluid infusions or administration of vasopressors. Short-term studies (20 min) in patients undergoing lumbar epidural anesthesia suggest that plasma volume may increase when hy

Stroke volume and sympathetic responses to lower-body negative pressure reveal new insight into circulatory shock in humans.

Abstract: We measured various hemodynamic responses and muscle sympathetic nerve activity (MSNA) in human subjects during a graded lower-body negative pressure (LBNP) protocol to test the hypotheses that: (1) reduced stroke volume (SV) is linearly related to increased MSNA; and (2) the onset of symptoms of impending cardiovascular collapse is associated with hypoadrenergic responses to central hypovolemia. We measured heart rates, arterial blood pressures, sympathetic neural activity (MSNA; peroneal nerve microneurography), and relative changes (% Δ) in SV (thoracic electrical bioimpedance) in 13 men during exposure to graded levels of LBNP. After a 12-min baseline data collection period, LBNP was initiated at −15 mm Hg for 12 min followed by continuous stepwise increments to −30, −45, and −60 mm Hg for 12 min each. Eight subjects completed the LBNP protocol (finishers), while the protocol was terminated prematurely during −60 mm Hg in five subjects due to onset of symptoms of cardiovascular collapse (nonfinishers). Of these subjects, we were able to record MSNA successfully throughout the LBNP protocol in four finishers and two nonfinishers. The relationship between average change in stroke volume and average change in MSNA was linear (% ΔMSNA=464–3.6 [% ΔSV], r 2 =0.98). On average, MSNA was greater in the nonfinishers at each level of LBNP compared to finishers, but peripheral resistance was lower. Our results support the hypothesis that MSNA activation is inversely related and linear to stroke volume reductions during central hypovolemia. Sympathetic withdrawal rather than hypoadrenergic function may represent a fundamental mechanism for the development of circulatory shock.

Monitoring of respiratory variations of aortic blood flow velocity using esophageal Doppler.

Abstract: The purpose of this study was to determine whether monitoring of respiratory changes in aortic blood flow velocity, recorded by esophageal Doppler, could be used to detect changes in volume depletion. Animal study. After general anesthesia and tracheotomy, ten New Zealand female rabbits, weighing 4–4.5 kg were studied under mechanical ventilation at a fixed tidal volume; during this time 5-ml blood samples were withdrawn (in increments up to a total of 30 ml) and then retransfused. At each step, systolic (SBP), diastolic (DBP), pulse (PP) pressures and maximum descending aortic blood flow (V) were recorded. Respiratory changes of V (ΔV), SBP (ΔSBP) and PP (ΔPP) were calculated as the difference of maximal and minimal values divided by their respective means and expressed as a percentage. The amount of blood withdrawn correlated negatively with SBP, DBP, PP and V and positively with ΔSBP, ΔPP and ΔV. Among these parameters, ΔV correlated best with the amount of blood withdrawn (r=0.89, p<0.001) and it was the most accurate index of volume depletion. Monitoring of the respiratory variation in V, calculated by esophageal Doppler technique, seems to be a highly accurate index of blood volume depletion and restitution.

Relation of Postural Vasovagal Syncope to Splanchnic Hypervolemia in Adolescents

Abstract: Background— The mechanisms of simple faint remain elusive. We propose that postural fainting is related to excessive thoracic hypovolemia and splanchnic hypervolemia during orthostasis compared with healthy subjects. Methods and Results— We studied 34 patients 12 to 22 years old referred for multiple episodes of postural faint and 11 healthy subjects. Subjects were studied in the supine position and during upright tilt to 70° for 30 minutes and subgrouped into S+, historical fainters who fainted during testing (n=24); S−, historical fainters who did not faint during testing (n=10); and control subjects. Supine venous occlusion plethysmography showed no differences between blood flows of the forearm and calf in S+, S−, or control. Cardiac index, total peripheral resistance, and blood volume were not different. Using impedance plethysmography, we assessed blood redistribution during upright tilt. This demonstrated decreased thoracic blood volume and increased splanchnic, pelvic, and leg blood volumes for al...

Reduced baroreflex control of heart period after bed rest is normalized by acute plasma volume restoration

Abstract: Adaptation to spaceflight or head-down-tilt bed rest leads to hypovolemia and an apparent abnormality of baroreflex regulation of cardiac period. In a previous study, we demonstrated that both chro...

Sinking brain syndrome: craniotomy can precipitate brainstem herniation in CSF hypovolemia.

Abstract: Intracranial hypotension associated with CSF hypovolemia can occur spontaneously from cryptic CSF leaks, after trauma, or from iatrogenic causes, especially lumbar puncture. It is not widely known that it increases the risk of complications from craniotomy. We present two cases in which patients with CSF hypovolemia experienced posture-dependent deteriorations in level of consciousness after craniotomy. ### Patient 1. A 59-year-old woman sought treatment for progressive headache. CT and MRI demonstrated bilateral subdural fluid collections with diffuse pachymeningeal enhancement and a left subdural hematoma with mild left to right shift. She had a craniotomy with evacuation of the hematoma and dural biopsy. This showed only thrombus and normal dura. Headache persisted postoperatively, and she became progressively more obtunded despite head elevation. CT showed bifrontal pneumocephalus and effacement of the suprasellar cistern. By postoperative day 5, she was responsive only to pain and had no voluntary eye movements. Pupils were reactive at 4 mm, but plantar responses were extensor. Neurology was consulted. Further history disclosed the preoperative headaches were orthostatic. Reanalysis of the radiologic …

Spontaneous breathing through an inspiratory impedance threshold device augments cardiac index and stroke volume index in a pediatric porcine model of hemorrhagic hypovolemia.

Abstract: Background: Hemorrhagic shock secondary to trauma is associated with poor survival. The impedance threshold device (ITD) has been shown to improve blood pressure and survival rates in an adult porcine model of hemorrhagic hypovolemia. Pediatric hemodynamics, anatomy, and physiology differ from adults. Evaluation of the ITD has not been previously assessed in a pediatric porcine model of hypovolemia induced by hemorrhage. Objective: To determine whether ITD-assisted breathing, with and without positive end-expiratory pressure, will improve key hemodynamic parameters following hypovolemia induced by hemorrhage in a pediatric porcine model. Methods: Intubated, anesthetized, hemodynamically stable, spontaneously breathing piglets were rapidly bled 40% of their calculated blood volume. Piglets' hemodynamic and intrathoracic pressures were continuously monitored during 10-min normovolemic baseline, bleed to hypotensive baseline, 10-min ITD-assisted breathing, 10 mins without ITD, 10-min ITD-assisted breathing randomized with or without positive end-expiratory pressure (3 cm H 2 O), 10 mins without ITD, reinfusion of shed blood, 10-min baseline following retum to normovolemia. The ITD had an inspiratory cracking pressure of -7 cm H 2 O. Transthoracic echocardiographic parameters were measured at the end of each 10-min period. Results: There was no significant difference in baseline assessments between groups. Systolic blood pressure, cardiac index, and stroke volume index were significantly greater during ITD-assisted breathing. There was a trend toward increased left ventricular end-diastolic dimension during ITD use. Heart rate, systemic vascular resistance index, left ventricular end-systolic dimension, and shortening fraction did not change significantly during ITD-assisted breathing. There was equivalent improvement in systolic blood pressure, cardiac index, and stroke volume index, when the ITD alone and ITD plus positive end-expiratory pressure were used. Conclusions: ITD-assisted breathing significantly augmented systolic blood pressure, cardiac index, and stroke volume index in this pediatric porcine model of hemorrhagic hypovolemia. These effects appear related to increased left ventricular preload and not by increased systemic vascular resistance or heart rate. These beneficial effects of ITD-assisted breathing are not changed by the addition of positive end-expiratory pressures of 3 cm H 2 O.

Pass the Salt Indications for and Implications of Using Hypertonic Saline

Abstract: Sodium is the most abundant extracellular ion. Historically, therapy with hypertonic saline was widely used for a variety of conditions. Currently, there are 3 primary indications for its use in critical care: hyponatremia, volume resuscitation, and brain injury. SIADH and CSW syndrome may require sodium replacement, but most cases of hyponatremia can be managed without administration of hypertonic saline. Studies of use of hypertonic saline in hypovolemia and brain injury are promising, but additional research is needed to better define optimal dosing regimens and to determine the relative risks associated with hypertonic saline versus conventional treatment for the management of patients with head injuries and for volume resuscitation in shock states.

Osmoregulation of vasopressin release and gene transcription under acute and chronic hypovolemia in rats.

Abstract: Although acute decreases in plasma volume are known to enhance the osmotically induced arginine vasopressin (AVP) release, it is unclear whether there is also such interaction at the level of gene transcription. It also remains to be established how sustained changes in plasma volume affect the osmoregulation. In this study, we examined how acute and chronic decreases in blood volume affected the osmoregulation of AVP release and gene transcription in rats. Acute hypovolemia was induced by intraperitoneal injection of polyethylene glycol (PEG), and chronic hypovolemia was induced by 3 days of water deprivation (WD) or 12 days of salt loading (SL). Rats were injected with isotonic or hypertonic saline, and plasma AVP levels and AVP heteronuclear (hn)RNA expression in the supraoptic and paraventricular nuclei, an indicator of gene transcription, were examined in relation to plasma osmolality in each group. Plasma AVP levels were correlated with plasma Na levels in all groups. Whereas the regression lines relating plasma AVP to Na were almost identical among control, WD, and SL groups, the thresholds of plasma Na for AVP release were significantly decreased only in the PEG group. AVP hnRNA levels were also correlated with plasma Na levels in control and PEG groups, and the thresholds were significantly decreased in the PEG group. In contrast, there was no significant correlation of AVP hnRNA and plasma Na levels in WD and SL groups. Thus it was demonstrated that acute and chronic reduction in plasma volume affected the osmoregulation of AVP release and gene transcription in different ways.

Fludrocortisone does not prevent orthostatic hypotension in astronauts after spaceflight.

Abstract: Background During stand/tilt tests after spaceflight, 20% of astronauts experience orthostatic hypotension and presyncope. Spaceflight-induced hypovolemia is a contributing factor. Fludrocortisone, a synthetic mineralocorticoid, has been shown to increase plasma volume and orthostatic tolerance in Earth-bound patients. The efficacy of fludrocortisone as a treatment for postflight hypovolemia and orthostatic hypotension in astronauts has not been studied. Our purpose was to test the hypothesis that astronauts who ingest fludrocortisone prior to landing would have less loss of plasma volume and greater orthostatic tolerance than astronauts who do not ingest fludrocortisone. Methods There were 25 male astronauts who were randomized into 2 groups: placebo (n = 18) and fludrocortisone (n = 7), and participated in stand tests 10 d before launch and 2-4 h after landing. Subjects took either 0.3 mg fludrocortisone or placebo orally 7 h prior to landing. Supine plasma and red cell volumes, supine and standing HR, arterial pressure, aortic outflow, and plasma norepinephrine and epinephrine were measured. Results On landing day, 2 of 18 in the placebo group and 1 of 7 in the fludrocortisone group became presyncopal (chi2 = 0.015, p = 0.90). Plasma volumes were significantly decreased after flight in the placebo group, but not in the fludrocortisone group. During postflight stand tests, standing plasma norepinephrine was significantly less in the fludrocortisone group compared with the placebo group. Conclusions Treatment with a single dose of fludrocortisone results in protection of plasma volume but no protection of orthostatic tolerance. Fludrocortisone is not recommended as a countermeasure for spaceflight-induced orthostatic intolerance.

Plasma albumin level as an indicator of severity of preeclampsia.

Abstract: We propose that hypoalbuminemia in preeclampsia is the result of reduced hepatic blood flow which is secondary to hypovolemia created by higher filtration pressure in the capillaries. Thus, hypoalbuminemia can be identified as an early sign in developing preeclampsia. We reviewed the medical records of 60 patients, aged 22-28, admitted with a diagnosis of preeclampsia during the third trimester of pregnancy. Normotensive patients served as a control group. Albumin levels were correlated with severity of the disorder. Levels between 3.0-3.5 g/dl were seen in both groups. All patients with severe preeclampsia had values below 3.0 gm/dl. Serum albumin levels may serve as an indicator of the severity of preeclampsia.

CSF hypovolemia vs intracranial hypotension in "spontaneous intracranial hypotension syndrome".

Abstract: To the Editor: Miyazawa et al.1 demonstrate that venous engorgement occurs in association with CSF hypovolemia and that this may occur in the absence of hypotension as measured by routine lumbar puncture. It is likely that progressive CSF hypovolemia leads to intracranial hypotension but that the intracranial pressure is also dependent on other variables. In mild to moderate CSF …

A comparison of changes in cardiac preload variables during graded hypovolemia and hypervolemia in mechanically ventilated dogs.

Abstract: We developed an online monitoring system to measure systolic blood pressure variation (SPV) and its down (dDown) and up components, along with pulse pressure variation (dPP). Using the system, we compared different cardiac preload indicators-such as stroke volume variation (SVV) and corrected flow time (FTc)-along with central venous pressure and pulmonary artery occlusion pressure in mechanically-ventilated dogs during normovolemia, graded hypovolemia (-200 and -350 mL), and hypervolemia (+200 and +350 mL). We simultaneously measured these preload indicators along with global hemodynamic variables and investigated their validity and limitations to access preload changes. SPV increased from 4.8 +/- 1.4 mm Hg at baseline to 11.2 +/- 1.8 mm Hg during hypovolemia (-350 mL), but it did not change significantly during hypervolemia. Similar changes were observed with dDown, dPP, and SVV. FTc, conversely, increased during hypervolemia but remained unchanged during hypovolemia. The results of this study indicate that SPV, dDown, dPP, and SVV are useful indicators of hypovolemia, but not of hypervolemia. Conversely, hypovolemia could not be detected reliably by FTc, but it does reflect blood volume changes during hypervolemia. Although SPV, dDown, and dPP measurements require no additional invasion and cost beyond arterial cannulation, their limits must be kept in mind for the monitoring of blood volume status in mechanically-ventilated patients.

Hemodialysis‐Induced Hypotension: Impact of Technologic Advances

Abstract: Hemodialysis-induced hypotension is one of the most serious complications in renal replacement therapy. The main cause of intradialytic hypotension is hypovolemia due to an imbalance between the amount of fluid removed and the refilling capacity of the intravascular compartment. Hypotension occurs when compensatory mechanisms for hypovolemia are overwhelmed by excessive fluid removal. As long as renal replacement therapy is limited to only a few hours per week, intradialytic hypotension will continue to be a relevant problem. Research has mainly focused on enlarging the compensatory capacity for ultrafiltration-induced hypovolemia. This article critically discusses the technical approaches that have been introduced into therapy in recent years with the promise of reducing dialysis-induced hypotensive episodes.

Medical treatment of intracerebral hemorrhage.

Abstract: Intracerebral hemorrhage (ICH) occurs as a result of bleeding into the brain parenchyma and formation of a focal hematoma. Treatment for ICH is primarily supportive, and outcome remains poor. Initial management is directed toward stabilizing breathing and circulation. Increased intracranial pressure is currently managed with osmotic agents (mannitol and glycerol); steroids, hypovolemia, controlled hyperventilation, and barbiturate coma can also be employed. Arterial blood pressure control is useful and requires adequate compliance to specific guidelines. Ultra-early hemostatic therapy may represent a promising tool to reduce early hematoma enlargement and to improve outcome.

Treating disc herniation and other conditions with leukocytes

Abstract: Leukocytes, which may include one or more of monocytes, macrophages, lymphocytes, and neutrophils, are harvested and administered to a region of the body In the preferred embodiment, leukocytes are harvested from the blood by plasmapherisis, a procedure known to those familiar with blood-banking techniques, and used to treat an intervertebral disc Plasmapherisis allows the removal of desired blood component(s) from a larger volume of blood than the technique described in the '000 Application Returning the non-desired blood components to the patient prior to withdraw of additional blood prevents complications that may occur from hypovolemia Thus, a larger number of leukocytes can be obtained with plasmapherisis than with centrifugation of blood removed during a single blood withdraw Plasmapherisis can also be used to harvest platelets to treat DDD, HNP and other non-disc-related conditions

Heat stress: characteristics, pathophysiology and avoidable mistakes.

Abstract: In August 2003 an exceptional heatwave was recorded in Europe. The authors would like to describe 6 patients for which the intensivist was called as a consultant. All patients had a skin temperature >40 degrees C, central nervous system impairment, severe hyponatremia [124.7 mEq/l+/-5.6 (range 117-130)] and severe metabolic acidosis [BE -6.28 mEq/l+/-3.55 (range -9.5-0), HCO3- 17.75 mEq/l+/-3.25 (range 13.4-21.9)]. All patients had decreased platelet count and coagulation abnormalities. Two patients were hypertensive, 4 hypotensive. The heat stress due to the hot environment is characterized by systemic inflammatory response (as in severe sepsis) and hemodynamic impairment (as in hypovolemic shock). The association between hypovolemia and altered microcirculation leads to cell energy failure with metabolic lactic acidosis. The energy failure may induce structural irreversible damage of mitochondria. It is possible to differentiate, during energy failure, the irreversible or reversible condition by volume loading and vasoactive drugs challenge tests. In fact, if the hemodynamic correction is associated with normalization of SvO2 with disappearance of metabolic acidosis, this suggests hemodynamic impairment with intact mitochondrial function. In contrast, if the hemodynamic improvement with normalization of SvO2 is associated and acidosis persists, this suggests irreversible structural mitochondrial damage. The threshold between reversibility and irreversibility is likely time dependent, as suggested by biochemical consideration and by 2 large randomized studies on hemodynamic treatment. The comparative analysis of these 2 studies suggests that the time of intervention may lead to significant differences in mortality. In these patients time is essential.

Decrease in left ventricular ejection time on digital arterial waveform during simulated hypovolemia in normal humans.

Abstract: Background:Left ventricular ejection time (LVET) measured in central arteries is modified during hypovolemia. We compared modifications of the pulse wave in a central artery (carotid) and in a peripheral artery (digital) during central hypovolemia induced by lower body negative pressure (LBNP) in co

Influence of progressive central hypovolemia on Hölder exponent distributions of cardiac interbeat intervals.

Abstract: The purpose of the study was to determine the dependency of the statistical properties of the R to R interval (RRI) time series on progressive central hypovolemia with lower body negative pressure. Two data-processing techniques based on wavelet transforms were used to determine the change in the nonstationary nature of the RRI time series with changing negative pressure. The results suggest that autonomic neural mechanism driving cardiac interbeat intervals during central hypovolemia go through various levels of multifractality, as determined by Holder exponent distributions.

Plasma volume and blood viscosity during 4 h sitting in a dry environment: effect of prehydration.

Abstract: Background Deep vein thrombosis and pulmonary thromboembolism are potential problems for travelers, including those who fly We hypothesized that prehydration with an electrolyte-glucose beverage (EGB) would be better than water for maintaining body fluid balance and preventing increased blood viscosity in immobilized men Methods There were 12 healthy men (24-38 yr) who participated in crossover trials of prehydration using EGB and H2O as well as a control condition (Con) with no prehydration Fluid intake was set at 6 ml x kg(-1) body weight (mean 418 ml) For each trial, subjects sat for 4 h at a dry-bulb temperature of 230-235 degrees C and a relative humidity of 18-36% Plasma volume (PV) and whole blood viscosity (Bvis) were determined every hour; routine laboratory hematological tests, urine volume, and body weight were recorded at 2 h and 4 h Results For Con, subjects lost approximately 110 ml h(-1); at 2 h, PV had decreased significantly by 34%, and Bvis had increased significantly by 93%, with no further change at 4 h For prehydration, retention of the consumed fluid at 2 h was significantly higher for EGB (57%) than for H2O (38%), while both drinks prevented significant change in PV and Bvis There were no significant differences between trials in coagulation variables, but Bvis measured at higher shear rates for EGB were significantly attenuated compared with Con Conclusion EGB and water prevented the increase of blood viscosity that occurred without prehydration EGB was better than water for maintaining body fluid balance and preventing hypovolemia

Blood substitute resuscitation as a treatment modality for moderate hypovolemia.

Abstract: Blood substitute resuscitation as a treatment modality for moderate hypovolemia (approximately 40% blood loss) in a canine model has been evaluated using Oxyglobin (Biopure Hemoglobin Glutamer-200/ Bovine; a hemoglobin-based oxygen-carrier) and Hespan (6% hetastarch; a nonoxygen-carrier) as resuscitants. Autologous (shed) blood served as control. Nine dogs were studied--after splenectomy, each dog was hemorrhaged (32-36 mL/kg; MAP = approximately 50 mmHg) and randomly assigned to the three resuscitation groups. Microvascular, systemic function and oxygenation characteristics were monitored and/or measured simultaneously in prehemorrhagic (baseline), posthemorrhagic and postresuscitation phases for correlation-real-time microvascular changes in the bulbar conjunctiva were noninvasively measured via computer-assisted intravital microscopy and systemic function and oxygenation changes were monitored and/or measured via instrumentation and devices incorporated into our bioengineering station in an operating room setting. Blood chemistry was also studied for relevant measurements. Prehemorrhagic microvascular characteristics were similar in all animals (venular diameter = 41 +/- 12 microm, A:V ratio = approximately 1:2, red-cell velocity = 0.5 +/- 0.3 mm/s). All animals also showed similar prehemorrhagic systemic function and oxygenation measurements comparable to a previous study and were consistent with normal measurements in dogs. At the completion of hemorrhaging to achieve moderate hypovolemia (approximately 40% blood loss with MAP at approximately 50 mmHg), all nine animals showed similar significant (P < 0.01) posthemorrhagic microvascular changes, including approximately 17% decrease in diameter (34 +/- 7 microm), A:V ratio = variable, and approximately 80% increase in velocity (0.9 +/- 0.5 mm/s). All animals also showed similar significant (P < 0.01) posthemorrhagic systemic function and oxygenation changes, with decreases in Hct, aHb(total), MPAP, MAP, SAP, DAP, CO, SVI, CaO2, and CvO2 and increases in HR and lactic acidosis. Shed blood (control) resuscitation restored posthemorrhagic microvascular changes close to prehemorrhagic values (diameter = 39 +/- 6 microm, A:V ratio = approximately 1:2, velocity = 0.6 +/- 0.4 mm/s). Oxyglobin and Hespan restored microvascular changes in similar manner close to prehemorrhagic values (Oxyglobin: diameter = 38 +/- 3 microm, A:V ratio = approximately 1:2, velocity = 0.6 +/- 0.4 mm/s; Hespan: diameter = 38 +/- 7 microm, A:V ratio = 1:2, velocity = 0.5 +/- 0.4 mm/s). After resuscitation, shed blood (control) restored all systemic function and oxygenation changes close to prehemorrhagic values. However, both Oxyglobin and Hespan resuscitation restored systemic function changes, but not oxygenation changes, to prehemorrhagic values. This was an interesting finding because of the different oxygen-carrying capability of Oxyglobin (oxygen-carrying) and Hespan (nonoxygen-carrying). The result suggests that either volume replenishment alone (and not oxygen-carrying capability) is needed to treat moderate hypovolemia or oxygenation measurements obtained by standard methods (oximetry, blood chemistry) may not reflect tissue oxygenation levels.